Apparatus for pulverizing coal or other fuel



MarchZS, 1930. J MULLIN 5 APPARATUS For: PULVERIZING COAL OR OTHER FUELFiled March so, 1929 :5 Sheets-Sheet 1 J mam.

March 25, 1930. J. MULLIN 1,751,525

APPARATUS FOR PULJERIZING COAL OR OTHER FUEL Filed March 50, 1929 5Sheets-Sheet 2 I [AWE/V708 S y'- MaZZin J. MULLIN March 25, 1 930.

APPARATUS FOR PULVERIZING. COAL OR OTHER FUEL Filed March 50, 1929 3SheetsShet 3 7G, is

Patented Mar. 25,- 1930 UNITED sr-A come mm, or nus-mm, ENGLAND Arum-rueiron runvnmzine con. on ornna rum.

Application fled March so, 1929, Serial no.

This invention relates to apparatus forulverizing coal or other fuelinto powdered orm for use more particularly in connection with thefiringof furnaces and the like, the chief object being to provide a simple-andmore eflicient constructional form of apparatus of this character.

According to this invention, thereis provided apparatus comprising arotatable drum adapted to'receive the fuel and havin internal means toeffect the ulverization t ereof, and also having circum erential slotsor openings in its periphery intermediate its ends to permit thedischarge of the pulverized fuel. Other features of the invention willappear from the following description and appended claims.

In order that the invention may be clearly understood and readilycarried into effect, the same will now be described more fully, by wayof example, with reference to the accompanying drawing, in which Figure1; and

Figure 1 is a longitudinal vertical sectional view of apparatusembodying the in- 2 vention;

Figure 2 is a plan view corresponding to Figure 3 is an elevation takenat right angles to Figure 1.

Referring to the drawings, the apparatus comprises a longitudinalrotatable drum (1 havin conical ends 6 and an intermediate cylin ricalportion 0 connected to the said ends and provided with circumferentialdischarge slots or openings d. Such discharge slots or openings (1conveniently are formed by spacedrings c. The drum is filled partly withballs e or the like of steel or other hard material and is; fitted witha preferably detachable lining f of chilled cast iron, steel, hardrubberor other appropriate material having spherical or'otherprojections. g to impart to the said balls a risingand falling motion inconjunction with similar projections on the intermediate portion 0,during rotationof the drum and thereby effect the pulverization of thefuel, the said lining being secured to the cylinder by means of bolts orother suitable fastening means. The cylinder a is supported axially ateach end theressnsvo, and in Great Britain April 2, 1928,

of by preferably water-cooled pedestal'bearings h on a bed-plate 11, butthe drum may be provided with circumferential tracks and be supported onrollers, according to requirements. The drum may be rotated, as by meansof toothed gearing j, 70 and shafting Z-operated by a preferablyvariable speed electric motor m, but any other form of prime mover maybe employed. In the example shown, the shafting Z is operated from themotor b a chain drive n. Coal or other fuel in t e form of relativelysmall cubes or lumps is fed into a relatively fixed hopper 0 associatedwith the drum at one end thereof, suitable feeder gear p being adaptedto act on the fuel to feed the same into the drum so as to bepulverized, the fine fuel falling through the aforesaid openings at inthe drum into the lower portion of an annular chambergsufroundingtheintermediate portion 0 of the drum, the said lower portion of thechamber 9 being provided with an automatic valve 1-. The said valve,which is shown pivotally mounted at s, is so adapted as to permit theweight of fine fuel to force it open and fall into an air supply pipe orconduit tleading to one end of the drum (1, the said valve being also soadapted as to provide against any reverse flow of the air, passingthrough the said conduit, entering the chamber 9. Such discharged finefuel is caught by the current of air passing through the said conduitwhich is connected to a fan u disposed exterior-1y of the drum anddriven by the aforesaid variable speed electric motor or other primemover as by means of a chain drive 1),, or driven by a separate electricmotor or other prime mover if desired. The disposition of the fanexteriorly of the cylinder and its arrangement so that it only forces.the air through the machine, serves to ensure less, wear and-tearthereof than in the case of the existing type of fan which, althoughexterticles of requisite fineness may be carried forward through aclassifier eduction pipe w and outlet pipe in to the furnace, storagebunker or other suitable place. If desired, the air forced through themachine may be heated in order to dry the fuel and increase the rate ofpulverization. In order to'provide against the leakage of powdered fuelat the trunnions or journals of the drum air may be led from the fandischarge pipe to annular chambers y afforded, for instance, around therelatively fixed inlet and discharge pipesassociated with the ends ofthe drum, so that any leakage will be into the .drum from the saidannular chambers owing to the slightly higher pressure therein. Leakageof powdered fuel at the joints of the annular chamber 9 with the drum isalso prevented by air at fan discharge pressure being admitted toannular chambers 2 arranged around the said joints, the pressure in thesaid chambers being greater than the pressure in the chamber 9. Thefeeder gear ;0 arranged with respect to the hopper 0 may be operated inany appropriate manner, such as, for instance, by means of a chain adriven by worm reduction gear at b from an extension of the main drivingshaft Z of the apparatus, the chain drive in the example shown includinga spring clutch device C. 1

It will be obvious that the output of the machine may be varied byaltering the speed of the motor or other prime mover and also bycontrolling a slide d associated with the fuel supply hopper. Further,the secondary air for complete combustion of the fuel in the furnace,when direct firing is resorted to, may be taken from the discharge pipeof the fan at a point, such as at 6, between the fan u and the valve 1',the supply being'regulated as by a damper or dampers in the said pipe.The fineness of the fuel may be controlled by regulating the air to thedrum.

I claim 1. ,A ball and drum pulverizing mill comprising a rotatabledrum, balls therein, and means for delivering material into one end ofthe drum, the drum having imperforate conical end portions and anintermediate cylindrical portion which is in free communication with theend portions and is provided with openings through which pulverizedmaterial is discharged.

2. A ball and drum pulverizing mill comprising a rotatable drum, ballstherein, and means for delivering material to the drum, the drum havingimperforate conical end portions and an intermediate cylindrical portionconsisting of axially spaced rings providing circumferential dischargeopenings.

3. A drum and ball pulverizing mill comprising a rotatable drum, ballstherein, and means for delivering material to one end of the'drum, thedrum having imperforate conical end portions and an intermediatecylindrical portion provided with discharge openings and provided uponthe inner surface of the conical end portions, with a lurality ofprojections whereby to cause the alls to rise and fall as the drumrotates.

4. A ball and drum pulverizing mill comchamber, a conduit extending pastsaid annu-,

lar chamber and arranged to receive material discharged past said valve,the conduit being connected at one end to one end of the drum, and meansfor delivering an air blast through the conduit.

5. A ball and drum pulverizing mill comprising a rotatable drum, ballstherein, means for delivering material into one end of the drum, thedrum having circumferential discharge openings between its ends, anannular chamber surrounding the discharge portion of the drum andprovided with a non-return valve permitting discharge ofmaterial fromthe chamber, a conduit extending past the annular chamber and arrangedto receive material discharging past the valve, the conduit having oneend connected to one end of the drum, means for delivering an air blastthrough the conduit, and means at the dischar e end of the conduit forreceiving material t erefrom and classifying the same, permitting thelarger pieces of material to return to the drum and the smaller piecesto be carried to a point of dischar e.

6. A all and drum pulverizing mill comprising a rotatable drum, ballstherein, means for delivering material into one end of the drum, thedrum being provided between its ends with circumferential dischargeopenings, an annular chamber surrounding the discharge openings toreceive the material passing therethrough, annular recesses around saidannular chamber at the joint between the same and the drum, annularrecesses around the bearings of the drum, and means for supplying airunder pressure to said recesses to prevent leakage of material.

JOHN MULLIN.

